Osteosarcoma of the distal femur

Case contributed by Dr Ali Abougazia

Presentation

Right lower thigh pain for a few months.

Patient Data

Age: 16
Gender: Female
X-ray

A right femoral distal metaphyseal osseous lytic lesion is seen with wide zone of transition and aggressive pattern of bone destruction (permeative), aggressive periosteal reaction (Codman's triangle) as well as osseous matrix and evidence of extra-osseous soft tissue component.

A right lower femoral shaft metadiaphyseal osteolytic exophytic lesion is seen showing a wide zone of transition with the adjacent normal bone marrow and encasing the postero-lateral circumference of the distal femoral shaft. The lesion elicits inhomogenous isointense T1 / T2 and high STIR signals with internal break-down foci of fluid signal. The lesion causes cortical destruction with and extra-osseous eccentric soft tissue component measuring 9.1 X 8 X 7.7 cm in orthogonal dimensions. The lesion and the soft tissue component show heterogeneous contrast enhancement.

The quadriceps femoris (mainly the vastus lateralis mucle) shows signal changes and post-contrast enhancement similar to the lesion and and appears stretched over the lesion.

No other lesions in the scanned bones or invasion of the popliteal neurovascular bundle.

Case Discussion

The highly aggressive nature, the location and the age group of the patient narrow the differential diagnosis of this lesion to either osteosarcoma or Ewing sarcoma, however the osseous matrix in the lesion and the age of the patient (older than 10 years) as well as the eccenteric metaphyseal location favor osteosarcoma.

Osteosarcoma is a malignant bone forming tumour and the second most common primary bone tumour after multiple myeloma. It accounts for about 20% of all primary bone tumours. Its primary form occurs in young patients (10-20 years). Its secondary form occurs in the elderly, usually secondary to malignant degeneration of Paget disease, extensive bone infarcts or post radiotherapy. Patients usually present with bone pain, occasionally accompanied by a soft-tissue mass or swelling. They typically occur at the metadiaphysis of tubular bones in the appendicular skeleton. Commonest site is around the knee.

Ewing sarcoma is the second most common primary bone tumour of childhood after osteosarcoma. Typically occurs in children (especially before 10 years old), and has a slight male predilection. Presentation is non-specific with local pain being by far the most common symptom. As far as location within long bones, the tumor is almost always metadiaphyseal or diaphyseal. Commonest site is around the knee.

PlayAdd to Share

Case information

rID: 31802
Case created: 28th Oct 2014
Last edited: 5th Oct 2015
Inclusion in quiz mode: Included

Updating… Please wait.
Loadinganimation

Alert accept

Error Unable to process the form. Check for errors and try again.

Alert accept Thank you for updating your details.